docs: def set_language(self, lang):
          """ Sets 'lang' parameter used to only fetch tweets within \
          a certain language
  
          :param lang: A 2-letter language code string (ISO 6391 compatible)
          :raises: TwitterSearchException
          """
  
          if lang in self.iso_6391:
              self.arguments.update({'lang': '%s' % lang})
          else:
              raise TwitterSearchException(1002)